A hypodermic needle has many applications in modern medicine. One application is to fit the hypodermic needle onto a syringe and to then insert the needle into a person's body for intra-muscular, subcutaneous, or intravenous injection of medications. Another application of the hypodermic needle is to coaxially mount a catheter over a hypodermic needle and to puncture a vein of a person's body with the needle. Following needle puncture, the over-the-needle (OTN) catheter is advanced into and retained in the vein, the needle is removed, and the catheter is connected to an intravenous line for fluid infusions into the vein.
A hypodermic needle entering into a patient's body is invariably contaminated by the patient's blood and body fluids. Following use of the needle, the needle presents a risk to physicians, nurses, and other health care personnel because the needle might transmit an infection or disease to such personnel if it were to accidentally puncture them. Thus, health care personnel are in constant danger of contracting infections and diseases, some of which may be deadly. Other potential victims of accidental needle punctures include sanitation workers who later dispose of garbage containing the hypodermic needle. The diseases which may be transmitted by a contaminated hypodermic needle include Immune Deficiency Virus, Hepatitis, Rabies, Kure, Encephalitis, and Arbor viruses. The outcome of contracting one of these diseases is often fatal because there are no known cures for any of these diseases. Often a needle puncture in a person's skin is so trivial that it remains unrecognized until the person becomes seriously ill.
Many existing OTN catheters suffer from penetration problems because of long length needles and unsecured needle supports. In addition, many existing OTN catheters still present the danger of causing needle pricks due to ineffective encasement of the puncturing needles following use.
The impact of needle stick injuries has shaken the healthcare industry. Several new products have been introduced and their disadvantages are now becoming apparent. An inventive improvement is required to remove these disadvantages.
The United States Congress has passed “Needle Stick Safety and Prevention Act (H.R.5178.ENR)”. The President has signed the bill into law that Is effective Apr. 18, 2002. The law, FDA, OSHA, Center For Disease Control, National Institute for Occupational Safety and Health and other regulatory bodies have also mandated and/or recommend several improvements in syringes.
It will be clear from the reading of the disclosure that the present invention does possess all the improvements deemed mandatory and/or recommended by regulatory agencies.
A number of improvements required and/or recommended by health care regulatory bodies contained in the present invention are listed below.
1. The syringe as well as retraction mechanism should be single hand operable, sparing another hand of physician for additional tasks. [Improved Industry Standard]
2. The switches and functional components are inseparable from the syringe and available in any emergencies. [Improved Industry Standard]
3. Activation of the retraction mechanism must occur from proximal plunger end. [Improved Industry Standard]
4. The worker's hand must remain behind the needle as it is covered. (FDA guidance on 510(k) Submission March 1995)
5. The safety feature must be an integral part of the device. (FDA guidance on 510(k) Submission March 1995)
6. The safety feature remains activated before disassembly and disposal. (FDA guidance on 510(k) Submission March 1995)
7. The safety feature should be simple and should require as little or no user action or training to use it safely and effectively. (FDA guidance on 510(k) Submission March 1995)
8. The safety feature is an integral part of the device. National Institute of Occupational Safety and health (NIOSH) desirable characteristics DHHS (NIOSH) alert. Publication No. 2000-108, November 99
9. The device preferably works passively. DHHS (NIOSH) alert. Publication No. 2000-108, November 99
10. The user can easily tell whether the safety feature is activated. DHHS (NIOSH) alert. Publication No. 2000-108, November 99
11. The safety feature cannot be deactivated and remains protective through disposal DHHS (NIOSH) alert. Publication No. 2000-108, November 99
12. The device performs reliably. DHHS (NIOSH) alert. Publication No. 2000-108, November 99
13. The device is easy to use and practical. DHHS (NIOSH) alert. Publication No. 2000-108, November 99
14. The device is safe and effective for patient care. DHHS (NIOSH) alert. Publication No. 2000-108, November 99.
15. Cost reduction by avoiding sharp container requirement for non-safe syringes Government Regulatory Agencies mandate use of the “sharp containers” at hospitals, physician offices and clinics as well as emergency rooms. These containers are strong steel boxes with a one way window through which used non-safety syringe and needles are dropped. The sharp protection service is operated by licensed companies that pick up the contents of the “Sharp containers” and dispose them at specially run facilities. This service is expensive and impacts on the cost of health care. Two safety syringes currently on the market do retract the needles after use, however the retracted needle and spring freely floats within the plunger cavity. If by chance the plunger is pulled off by minimum efforts the potential of needle stick injury does exist. FDA requires sharp containers for these because there is a chance of the needle stick injury. It adds to the expense.
One purpose of inventing the present safety syringe is to lock the retracted needle securely within the interlocked syringe itself rather than sharp container and save the expense. It is essential that the entire syringe must be interlocked and disposed off in biological recyclable waste to avoid the expense of sharp container fees. This objective is incorporated in the present invention
16. Premature disablement of devices. Advance of plunger in the barrel is a normal function of the syringe to inject the medicine. However in two devices on market retraction of the needle and disablement of syringe results from advance of the plunger within the barrel cavity, even before physician has a chance to use the syringe for patient. The syringe is wasted. The safety mechanism incorporated in the present invention and procedure of use avoids this accidental retraction and disablement.
17. Low dead space. At the end of the injection, medicine still remains within the nozzle and the female luer end. The cost of biotechnology medicines such as Epo, and newer insulins are very high and wastage is unacceptable. The present invention avoids the female luer connector that connects hypodermic needle with the nozzle—the cause of dead space.
18. Aerosolization. In certain devices on the market, after the injection of the medicine and advance of the plunger, a spring is released and the needle and spring flies back within the air-filled plunger. When the needle shoots back the air escapes out through the open needle due to the backward momentum and causes the fluid/medicine to escape from the needle. The escaping fluid may be contaminated.
The FDA has allowed the use of such syringes only for intra-muscular and subcutaneous application. Further it requires on use of such syringes that the retraction must be initiated and completed when the needle of the syringe is still within the body of the patient.
In the present invention the proximal end of the needle is closed and glued to the needle holder. Further the exit and entry of the fluid occurs at the peripheral wall of the needle, which is a zero velocity zone during needle retraction, and heavy construction. Also, the weight of the needle holder arm dampens the retroactive velocity of the needle. A reactive aerosolization is therefore not likely to occur, i.e., the present invention avoids aerosol problems.
19. Hydraulic disablement. Robust design of the present invention prevents disablement of retractable needle syringe that could result from increased hydraulic pressure inside the barrel.
Accordingly, there exists a need for a hypodermic needle assembly which overcomes the above-noted drawbacks associated with many existing assemblies.
The problem of suffering accidental needle punctures is well recognized. As a result, enormous inventive effort has been devoted to concealing the sharp needle point of hypodermic needles. Such efforts are described in the present applicant's U.S. Pat. No. 5,338,311, issued Aug. 16, 1994 and U.S. Pat. No. 6,156,013, issued Dec. 5, 2000.
Apart from the above patents, in certain of the syringes that are in the market, the hypodermic needle is assembled within the compression spring and installed in the nozzle of the syringe by a bushing or “O” ring. After injection of the medicine the bushing is displaced forward by plunger end. The displacement of the bushing releases the spring and the needle as well as the plug in the plunger cavity. The retracted spring, hypodermic needle and plug freely float in the plunger.
In situations (1) when the plunger is pushed fast before medicine could escape, (2) When the medicine is viscous and needs higher gradient to escape through the needle, (3) when the needle is thin and offers resistance, (4) when there is partial block in needle or has been inserted in thick tissue, hydraulic force generated in barrel displaces the bushing causes retraction. This happens even though plunger is not advanced and medicine is still in the syringe. The present invention prevents this mishap because of mechanical continuity and robust design.